Electroacoustic transducers typically include a pair of spaced permanent magnets forming a magnetic gap, a coil having a tunnel therethrough, and a reed armature. The armature is attached to a diaphragm by a drive rod. In normal operation, the armature does not contact the magnets or the coil. The armature can be easily damaged by over-deflection if the transducer experiences a shock, e.g., from being dropped. Because decreasing the size of an electroacoustic transducer decreases the tolerance of the transducer, the affect of shock on transducers becomes more significant as smaller transducers are designed.
One method of providing shock protection to a transducer is to limit the degree of deflection of the armature. For example, U.S. patent application Ser. No. 08/416,887, filed on Jun. 2, 1995, and allowed on Jan. 7, 1997, discloses a formation and/or a restriction on the armature to limit the deflection of the armature.
Magnetic fluid is known for its use in loudspeakers to dissipate heat by increasing the thermal conduction from the voice coil to the metal motor components. Loudspeakers require these heat dissipaters because they are very inefficient, and therefore, most of the power required to operate the loudspeakers is converted into heat.